Two-piece/full face sheet metal disk wheels, each including a disk with a full face structure which utilizes an outer peripheral portion of the disk as a front-side flange of a rim, may be classified in two types such as an in-turned flange type and a male-female type.
The wheel of the former in-turned flange type generally includes an in-turned flange 15 for prevention of a decrease in strength of a rim portion by welding, as designated by reference numeral 14 in FIG. 5.
The two-piece/full face sheet metal disk wheel of the in-turned flange type is disclosed in U.S. Pat. No. 4,610,482, wherein an unsymmetrical rim 12 of a single-sided flange type as shown in FIG. 6 and a disk 13 illustrated in FIG. 7 are centered and fixed to each other by means of a temporary assembling fixture. Under such condition, the disk and the rim are welded to each other at a portion represented by the reference 14 in FIG. 5.
The unsymmetrical rim 12 of FIG. 6 is manufactured by means of the well-known conventional roll forming.
In the two-piece/full face sheet metal disk wheel of the latter male-female type, for the purpose of facilitating positioning when the rim and the disk are assembled and welded to each other, the rim and the disk are made to act as a male member and as a female member (the male-female type), respectively, and fitted to each other (see FIG. 8).
The rim 18 used in this male-female type two-piece/full face sheet metal disk wheel includes an engagement portion formed by cutting for removing a front-side flange portion 24 of the rim produced for use in the two-piece disk wheel by the well-known conventional roll forming, as illustrated in FIG. 9.
In the disk 19, as shown in FIG. 10, a portion indicated by reference numeral 25 of a plate material which has been pressed, is cut and removed to thereby form an engagement portion 22.
The engagement portion 22 of the disk 19 is fitted in the engagement portion 21 of the rim 18. Subsequently, the rim 18 and the disk 19 are welded to each other, as depicted by reference numeral 20. During welding, a fixture is used for fixedly retaining the rim 18 and the disk 19.
In the above-described prior art, the former example, that is, the two-piece/full face sheet metal disk wheel of the in-turned flange type has such advantages that a convex portion formed by weld metal can be minimized in size and that a sufficient depth of weld penetration and a welding strength can readily be ensured, because a V-groove is defined in the welding portion 14 between the rim 12 and the disk 13. On the other hand, however, it includes a serious deft since it is difficult to ensure an accuracy in positioning the axial centers of the rim 12 and the disk 13 by means of the fixture and to prevent distortion by heat during welding. As a result, it is also hard to steadily obtain accuracy of runout of the wheel.
In the latter example, that is, the two-piece/full face sheet metal disk wheel of the male-female type, because the engagement portion 21 of the rim 18 and the engagement portion 22 of the disk 19 respectively have small distances in a horizontal direction of the drawings, an engagement tolerance with a high accuracy is required in both engagement portions. More specifically, if they are too tight with respect to each other, they cannot often be engaged with each other. On the other hand, if they are loosely engaged with each other, a centering accuracy is decreased, so that distortion caused by heat during welding cannot be effectively prevented.
Also, this type of wheel has such problems that the fixture is required when assembling and welding the rim and the disk, and that a surface of the welding bead 20 must be finished by grinding.
Further, in the case where the V-groove is provided in the welding portion through cutting in order to reduce the welding bead to have a size as small as possible and to ensure the weld penetration, a defect of burn through is liable to occur during welding.